Problem: $\left(x + 6\right)\left(-7x - 8\right) = \ ?$
$= x \cdot \left(-7x - 8\right) + 6 \cdot \left(-7x - 8\right)$ $= \left( x \cdot -7x \right) + \left( x \cdot -8 \right) + \left( 6 \cdot -7x \right) + \left( 6 \cdot -8 \right)$ $= -7x^2 + \left( x \cdot -8 \right) + \left( 6 \cdot -7x \right) + \left( 6 \cdot -8 \right)$ $= -7x^2 + \left( -8x - 42x \right) + \left( 6 \cdot -8 \right)$ $= -7x^2 - 50x + \left( 6 \cdot -8 \right)$ $= -7x^2 - 50x - 48$